1. Field of the Invention
This invention relates to a forceps instrument, such as a biopsy forceps and a grasping forceps, and more particularly to an operating portion of a forceps instrument.
2. Description of Related Art
As shown in FIGS. 1 and 2, an operating portion 3 of a conventional forceps instrument disclosed in Japanese Laid-Open Utility Model Application, Publication No. 58-160010 includes a flexible sheath 1; an operating wire 22 passing through the flexible sheath 1 for operating a treating portion 2 provided at the distal end of the flexible sheath 1; an operating body 10 provided at the proximal end of the flexible sheath 1; and a slider 12 slidably mounted on the outer periphery of the operating body 10. A holding plate 14 receiving a stopper 24 at the proximal end of the operating wire 22 is inserted into a slit portion 30 of the operating body 10, and the holding plate 14 is fitted into the slider 12 from the state shown in FIG. 3.
In this operating portion 3, in order to prevent the stopper 24 from being drawn out from the holding plate 14, an open portion 15 at the distal end of the holding plate 14 is closed in the slider 12 under a compressive force. Thus, after the operating portion 3 is assembled, the holding plate 14 is always under a radial compressive force. Moreover, when the slider 12 is slided by exerting a force, the force is also exerted on the holding plate 14 so that the holding plate 14 is susceptible to breakage in the vicinity of the bottom of its opening 15. Further, since the holding plate 14 is thinner than the slit portion 30 so as to be inserted into the slit portion 30, the force from the slider 12 will be concentrated on an area without being dispersed, which is also a cause of breakage.